The Chill-Its Lightweight Phase Change Cooling Vest helps to keep workers cooler, safer and more productive. Its phase change cooling material maintains a 64°F\/18°C temperature for up to two hours when activated. The vest's adjustable hook and loop closures around the waist provide a customized fit for different body types. The heavy-duty front zipper makes for easy on\/off, while the two front zippered pockets can be used to store small accessories. Phase Change Cooling Packs not included. There are many ways to activate your cooling vest. Simply place the four removable packs in a cooler of ice water for five minutes; freezer for eight minutes; refrigerator for 12 minutes; or near an air conditioner for one hour. The cooling pack should be washed by hand with a mild detergent and warm water. Do not machine wash or machine dry. The fabric vest is machine washable with mild soap.